This invention relates generally to telephone accessories, and more particularly to the recently developed, modular type telephones that have a single jack for plugging into a single opening of a wall-mounted socket.
It is well known that considerable misuse of a telephone occurs, especially in business firms where unauthorized persons use the company telephones for making their own personal telephone calls so that the firm is obliged to pay for them. This situation is objectionable and is therefore in need of an improvement.